Dual-Wavelength Photosensitizer Based on Phthalocyanine Nanodots for Multifunctional Composites with Enhanced Photodynamic Antibacterial, Photothermal Performance, and UV Protection

Designing efficient near-infrared photosensitive molecules and excellent photosensitive materials is a major challenge in the fields of photodynamic antibacterial and photothermal energy conversion. The Förster resonance energy transfer shows much promise for enhancing the photodynamic antibacterial property and photothermal performance. Herein, a novel water-soluble dual-band enhanced naphthylimide functionalized phthalocyanine photosensitizer is designed and synthesized. The designed dual-band enhanced photosensitizer, 2,9(10),16(17),23(24)-Tetrakis[N-Benzyl-N,N'-dimethyl-1-propanaminium-4-(N-hydroxyethyl)-1,8-naphthylimino] phthalocyanine Zinc(II) (NAPc-N), can self-assemble by the π–π stacking interactions to form nanodots with a size of ≈40–50 nm. Nanodot composites prepared using waterborne polyurethane (WPU), exhibit dual-wavelength photodynamic antibacterial at 440 and 680 nm irradiations, efficiently photothermal conversion, and excellent UV protection (UPF) performances. The produced singlet oxygen amount by NAPc-N shows tremendous enhancement in dual-wavelength irradiations. After 30 min under the blue and infrared lights, the antibacterial rate of NAPc-N against Staphylococcus aureus and Escherichia coli reaches 99.99%. The temperature of the NAPc-N composite can be heated up to 60 °C and the UPF value can be up to 128.23. These dual-wavelength enhanced photosensitizer nanodots hold significant potential for advanced photodynamic materials and biomaterials applications.